2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
6 * Definitions for the TCP module.
8 * Version: @(#)tcp.h 1.0.5 05/23/93
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
21 #define FASTRETRANS_DEBUG 1
23 #include <linux/list.h>
24 #include <linux/tcp.h>
25 #include <linux/bug.h>
26 #include <linux/slab.h>
27 #include <linux/cache.h>
28 #include <linux/percpu.h>
29 #include <linux/skbuff.h>
30 #include <linux/dmaengine.h>
31 #include <linux/crypto.h>
32 #include <linux/cryptohash.h>
33 #include <linux/kref.h>
35 #include <net/inet_connection_sock.h>
36 #include <net/inet_timewait_sock.h>
37 #include <net/inet_hashtables.h>
38 #include <net/checksum.h>
39 #include <net/request_sock.h>
43 #include <net/tcp_states.h>
44 #include <net/inet_ecn.h>
47 #include <linux/seq_file.h>
48 #include <linux/memcontrol.h>
50 extern struct inet_hashinfo tcp_hashinfo;
52 extern struct percpu_counter tcp_orphan_count;
53 extern void tcp_time_wait(struct sock *sk, int state, int timeo);
55 #define MAX_TCP_HEADER (128 + MAX_HEADER)
56 #define MAX_TCP_OPTION_SPACE 40
59 * Never offer a window over 32767 without using window scaling. Some
60 * poor stacks do signed 16bit maths!
62 #define MAX_TCP_WINDOW 32767U
64 /* Offer an initial receive window of 10 mss. */
65 #define TCP_DEFAULT_INIT_RCVWND 10
67 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
68 #define TCP_MIN_MSS 88U
70 /* The least MTU to use for probing */
71 #define TCP_BASE_MSS 512
73 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
74 #define TCP_FASTRETRANS_THRESH 3
76 /* Maximal reordering. */
77 #define TCP_MAX_REORDERING 127
79 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
80 #define TCP_MAX_QUICKACKS 16U
83 #define TCP_URG_VALID 0x0100
84 #define TCP_URG_NOTYET 0x0200
85 #define TCP_URG_READ 0x0400
87 #define TCP_RETR1 3 /*
88 * This is how many retries it does before it
89 * tries to figure out if the gateway is
90 * down. Minimal RFC value is 3; it corresponds
91 * to ~3sec-8min depending on RTO.
94 #define TCP_RETR2 15 /*
95 * This should take at least
96 * 90 minutes to time out.
97 * RFC1122 says that the limit is 100 sec.
98 * 15 is ~13-30min depending on RTO.
101 #define TCP_SYN_RETRIES 6 /* This is how many retries are done
102 * when active opening a connection.
103 * RFC1122 says the minimum retry MUST
104 * be at least 180secs. Nevertheless
105 * this value is corresponding to
106 * 63secs of retransmission with the
107 * current initial RTO.
110 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
111 * when passive opening a connection.
112 * This is corresponding to 31secs of
113 * retransmission with the current
117 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
118 * state, about 60 seconds */
119 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
120 /* BSD style FIN_WAIT2 deadlock breaker.
121 * It used to be 3min, new value is 60sec,
122 * to combine FIN-WAIT-2 timeout with
126 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
128 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
129 #define TCP_ATO_MIN ((unsigned)(HZ/25))
131 #define TCP_DELACK_MIN 4U
132 #define TCP_ATO_MIN 4U
134 #define TCP_RTO_MAX ((unsigned)(120*HZ))
135 #define TCP_RTO_MIN ((unsigned)(HZ/5))
136 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
137 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
138 * used as a fallback RTO for the
139 * initial data transmission if no
140 * valid RTT sample has been acquired,
141 * most likely due to retrans in 3WHS.
144 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
145 * for local resources.
148 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
149 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
150 #define TCP_KEEPALIVE_INTVL (75*HZ)
152 #define MAX_TCP_KEEPIDLE 32767
153 #define MAX_TCP_KEEPINTVL 32767
154 #define MAX_TCP_KEEPCNT 127
155 #define MAX_TCP_SYNCNT 127
157 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
159 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
160 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
161 * after this time. It should be equal
162 * (or greater than) TCP_TIMEWAIT_LEN
163 * to provide reliability equal to one
164 * provided by timewait state.
166 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host
167 * timestamps. It must be less than
168 * minimal timewait lifetime.
174 #define TCPOPT_NOP 1 /* Padding */
175 #define TCPOPT_EOL 0 /* End of options */
176 #define TCPOPT_MSS 2 /* Segment size negotiating */
177 #define TCPOPT_WINDOW 3 /* Window scaling */
178 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
179 #define TCPOPT_SACK 5 /* SACK Block */
180 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
181 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
182 #define TCPOPT_EXP 254 /* Experimental */
183 /* Magic number to be after the option value for sharing TCP
184 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
186 #define TCPOPT_FASTOPEN_MAGIC 0xF989
192 #define TCPOLEN_MSS 4
193 #define TCPOLEN_WINDOW 3
194 #define TCPOLEN_SACK_PERM 2
195 #define TCPOLEN_TIMESTAMP 10
196 #define TCPOLEN_MD5SIG 18
197 #define TCPOLEN_EXP_FASTOPEN_BASE 4
198 #define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
199 #define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
200 #define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
201 #define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
203 /* But this is what stacks really send out. */
204 #define TCPOLEN_TSTAMP_ALIGNED 12
205 #define TCPOLEN_WSCALE_ALIGNED 4
206 #define TCPOLEN_SACKPERM_ALIGNED 4
207 #define TCPOLEN_SACK_BASE 2
208 #define TCPOLEN_SACK_BASE_ALIGNED 4
209 #define TCPOLEN_SACK_PERBLOCK 8
210 #define TCPOLEN_MD5SIG_ALIGNED 20
211 #define TCPOLEN_MSS_ALIGNED 4
213 /* Flags in tp->nonagle */
214 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
215 #define TCP_NAGLE_CORK 2 /* Socket is corked */
216 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
218 /* TCP thin-stream limits */
219 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
221 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
222 #define TCP_INIT_CWND 10
224 /* Bit Flags for sysctl_tcp_fastopen */
225 #define TFO_CLIENT_ENABLE 1
226 #define TFO_SERVER_ENABLE 2
227 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
229 /* Process SYN data but skip cookie validation */
230 #define TFO_SERVER_COOKIE_NOT_CHKED 0x100
231 /* Accept SYN data w/o any cookie option */
232 #define TFO_SERVER_COOKIE_NOT_REQD 0x200
234 /* Force enable TFO on all listeners, i.e., not requiring the
235 * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen.
237 #define TFO_SERVER_WO_SOCKOPT1 0x400
238 #define TFO_SERVER_WO_SOCKOPT2 0x800
239 /* Always create TFO child sockets on a TFO listener even when
240 * cookie/data not present. (For testing purpose!)
242 #define TFO_SERVER_ALWAYS 0x1000
244 extern struct inet_timewait_death_row tcp_death_row;
246 /* sysctl variables for tcp */
247 extern int sysctl_tcp_timestamps;
248 extern int sysctl_tcp_window_scaling;
249 extern int sysctl_tcp_sack;
250 extern int sysctl_tcp_fin_timeout;
251 extern int sysctl_tcp_keepalive_time;
252 extern int sysctl_tcp_keepalive_probes;
253 extern int sysctl_tcp_keepalive_intvl;
254 extern int sysctl_tcp_syn_retries;
255 extern int sysctl_tcp_synack_retries;
256 extern int sysctl_tcp_retries1;
257 extern int sysctl_tcp_retries2;
258 extern int sysctl_tcp_orphan_retries;
259 extern int sysctl_tcp_syncookies;
260 extern int sysctl_tcp_fastopen;
261 extern int sysctl_tcp_retrans_collapse;
262 extern int sysctl_tcp_stdurg;
263 extern int sysctl_tcp_rfc1337;
264 extern int sysctl_tcp_abort_on_overflow;
265 extern int sysctl_tcp_max_orphans;
266 extern int sysctl_tcp_fack;
267 extern int sysctl_tcp_reordering;
268 extern int sysctl_tcp_dsack;
269 extern int sysctl_tcp_wmem[3];
270 extern int sysctl_tcp_rmem[3];
271 extern int sysctl_tcp_app_win;
272 extern int sysctl_tcp_adv_win_scale;
273 extern int sysctl_tcp_tw_reuse;
274 extern int sysctl_tcp_frto;
275 extern int sysctl_tcp_low_latency;
276 extern int sysctl_tcp_dma_copybreak;
277 extern int sysctl_tcp_nometrics_save;
278 extern int sysctl_tcp_moderate_rcvbuf;
279 extern int sysctl_tcp_tso_win_divisor;
280 extern int sysctl_tcp_mtu_probing;
281 extern int sysctl_tcp_base_mss;
282 extern int sysctl_tcp_workaround_signed_windows;
283 extern int sysctl_tcp_slow_start_after_idle;
284 extern int sysctl_tcp_max_ssthresh;
285 extern int sysctl_tcp_thin_linear_timeouts;
286 extern int sysctl_tcp_thin_dupack;
287 extern int sysctl_tcp_early_retrans;
288 extern int sysctl_tcp_limit_output_bytes;
289 extern int sysctl_tcp_challenge_ack_limit;
291 extern atomic_long_t tcp_memory_allocated;
292 extern struct percpu_counter tcp_sockets_allocated;
293 extern int tcp_memory_pressure;
296 * The next routines deal with comparing 32 bit unsigned ints
297 * and worry about wraparound (automatic with unsigned arithmetic).
300 static inline bool before(__u32 seq1, __u32 seq2)
302 return (__s32)(seq1-seq2) < 0;
304 #define after(seq2, seq1) before(seq1, seq2)
306 /* is s2<=s1<=s3 ? */
307 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
309 return seq3 - seq2 >= seq1 - seq2;
312 static inline bool tcp_out_of_memory(struct sock *sk)
314 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
315 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
320 static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
322 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
323 int orphans = percpu_counter_read_positive(ocp);
325 if (orphans << shift > sysctl_tcp_max_orphans) {
326 orphans = percpu_counter_sum_positive(ocp);
327 if (orphans << shift > sysctl_tcp_max_orphans)
333 extern bool tcp_check_oom(struct sock *sk, int shift);
335 /* syncookies: remember time of last synqueue overflow */
336 static inline void tcp_synq_overflow(struct sock *sk)
338 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
341 /* syncookies: no recent synqueue overflow on this listening socket? */
342 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
344 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
345 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
348 extern struct proto tcp_prot;
350 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
351 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
352 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
353 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
354 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
356 extern void tcp_init_mem(struct net *net);
358 extern void tcp_tasklet_init(void);
360 extern void tcp_v4_err(struct sk_buff *skb, u32);
362 extern void tcp_shutdown (struct sock *sk, int how);
364 extern void tcp_v4_early_demux(struct sk_buff *skb);
365 extern int tcp_v4_rcv(struct sk_buff *skb);
367 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
368 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
370 extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
371 size_t size, int flags);
372 extern void tcp_release_cb(struct sock *sk);
373 extern void tcp_write_timer_handler(struct sock *sk);
374 extern void tcp_delack_timer_handler(struct sock *sk);
375 extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
376 extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
377 const struct tcphdr *th, unsigned int len);
378 extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
379 const struct tcphdr *th, unsigned int len);
380 extern void tcp_rcv_space_adjust(struct sock *sk);
381 extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
382 extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
383 extern void tcp_twsk_destructor(struct sock *sk);
384 extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
385 struct pipe_inode_info *pipe, size_t len,
388 static inline void tcp_dec_quickack_mode(struct sock *sk,
389 const unsigned int pkts)
391 struct inet_connection_sock *icsk = inet_csk(sk);
393 if (icsk->icsk_ack.quick) {
394 if (pkts >= icsk->icsk_ack.quick) {
395 icsk->icsk_ack.quick = 0;
396 /* Leaving quickack mode we deflate ATO. */
397 icsk->icsk_ack.ato = TCP_ATO_MIN;
399 icsk->icsk_ack.quick -= pkts;
404 #define TCP_ECN_QUEUE_CWR 2
405 #define TCP_ECN_DEMAND_CWR 4
406 #define TCP_ECN_SEEN 8
416 extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
418 const struct tcphdr *th);
419 extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
420 struct request_sock *req,
421 struct request_sock **prev,
423 extern int tcp_child_process(struct sock *parent, struct sock *child,
424 struct sk_buff *skb);
425 extern void tcp_enter_loss(struct sock *sk, int how);
426 extern void tcp_clear_retrans(struct tcp_sock *tp);
427 extern void tcp_update_metrics(struct sock *sk);
428 extern void tcp_init_metrics(struct sock *sk);
429 extern void tcp_metrics_init(void);
430 extern bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check);
431 extern bool tcp_remember_stamp(struct sock *sk);
432 extern bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
433 extern void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
434 extern void tcp_disable_fack(struct tcp_sock *tp);
435 extern void tcp_close(struct sock *sk, long timeout);
436 extern void tcp_init_sock(struct sock *sk);
437 extern unsigned int tcp_poll(struct file * file, struct socket *sock,
438 struct poll_table_struct *wait);
439 extern int tcp_getsockopt(struct sock *sk, int level, int optname,
440 char __user *optval, int __user *optlen);
441 extern int tcp_setsockopt(struct sock *sk, int level, int optname,
442 char __user *optval, unsigned int optlen);
443 extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
444 char __user *optval, int __user *optlen);
445 extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
446 char __user *optval, unsigned int optlen);
447 extern void tcp_set_keepalive(struct sock *sk, int val);
448 extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
449 extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
450 size_t len, int nonblock, int flags, int *addr_len);
451 extern void tcp_parse_options(const struct sk_buff *skb,
452 struct tcp_options_received *opt_rx,
453 int estab, struct tcp_fastopen_cookie *foc);
454 extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
457 * TCP v4 functions exported for the inet6 API
460 extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
461 extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
462 extern struct sock * tcp_create_openreq_child(struct sock *sk,
463 struct request_sock *req,
464 struct sk_buff *skb);
465 extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
466 struct request_sock *req,
467 struct dst_entry *dst);
468 extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
469 extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
471 extern int tcp_connect(struct sock *sk);
472 extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
473 struct request_sock *req,
474 struct tcp_fastopen_cookie *foc);
475 extern int tcp_disconnect(struct sock *sk, int flags);
477 void tcp_connect_init(struct sock *sk);
478 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
479 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
480 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
482 /* From syncookies.c */
483 extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
484 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
485 struct ip_options *opt);
486 #ifdef CONFIG_SYN_COOKIES
487 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
490 static inline __u32 cookie_v4_init_sequence(struct sock *sk,
498 extern __u32 cookie_init_timestamp(struct request_sock *req);
499 extern bool cookie_check_timestamp(struct tcp_options_received *opt,
500 struct net *net, bool *ecn_ok);
502 /* From net/ipv6/syncookies.c */
503 extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
504 #ifdef CONFIG_SYN_COOKIES
505 extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
508 static inline __u32 cookie_v6_init_sequence(struct sock *sk,
517 extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
519 extern bool tcp_may_send_now(struct sock *sk);
520 extern int __tcp_retransmit_skb(struct sock *, struct sk_buff *);
521 extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
522 extern void tcp_retransmit_timer(struct sock *sk);
523 extern void tcp_xmit_retransmit_queue(struct sock *);
524 extern void tcp_simple_retransmit(struct sock *);
525 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
526 extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
528 extern void tcp_send_probe0(struct sock *);
529 extern void tcp_send_partial(struct sock *);
530 extern int tcp_write_wakeup(struct sock *);
531 extern void tcp_send_fin(struct sock *sk);
532 extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
533 extern int tcp_send_synack(struct sock *);
534 extern bool tcp_syn_flood_action(struct sock *sk,
535 const struct sk_buff *skb,
537 extern void tcp_push_one(struct sock *, unsigned int mss_now);
538 extern void tcp_send_ack(struct sock *sk);
539 extern void tcp_send_delayed_ack(struct sock *sk);
540 extern void tcp_send_loss_probe(struct sock *sk);
541 extern bool tcp_schedule_loss_probe(struct sock *sk);
544 extern void tcp_cwnd_application_limited(struct sock *sk);
545 extern void tcp_resume_early_retransmit(struct sock *sk);
546 extern void tcp_rearm_rto(struct sock *sk);
547 extern void tcp_reset(struct sock *sk);
550 extern void tcp_init_xmit_timers(struct sock *);
551 static inline void tcp_clear_xmit_timers(struct sock *sk)
553 inet_csk_clear_xmit_timers(sk);
556 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
557 extern unsigned int tcp_current_mss(struct sock *sk);
559 /* Bound MSS / TSO packet size with the half of the window */
560 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
564 /* When peer uses tiny windows, there is no use in packetizing
565 * to sub-MSS pieces for the sake of SWS or making sure there
566 * are enough packets in the pipe for fast recovery.
568 * On the other hand, for extremely large MSS devices, handling
569 * smaller than MSS windows in this way does make sense.
571 if (tp->max_window >= 512)
572 cutoff = (tp->max_window >> 1);
574 cutoff = tp->max_window;
576 if (cutoff && pktsize > cutoff)
577 return max_t(int, cutoff, 68U - tp->tcp_header_len);
583 extern void tcp_get_info(const struct sock *, struct tcp_info *);
585 /* Read 'sendfile()'-style from a TCP socket */
586 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
587 unsigned int, size_t);
588 extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
589 sk_read_actor_t recv_actor);
591 extern void tcp_initialize_rcv_mss(struct sock *sk);
593 extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
594 extern int tcp_mss_to_mtu(struct sock *sk, int mss);
595 extern void tcp_mtup_init(struct sock *sk);
596 extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
597 extern void tcp_init_buffer_space(struct sock *sk);
599 static inline void tcp_bound_rto(const struct sock *sk)
601 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
602 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
605 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
607 return (tp->srtt >> 3) + tp->rttvar;
610 extern void tcp_set_rto(struct sock *sk);
612 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
614 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
615 ntohl(TCP_FLAG_ACK) |
619 static inline void tcp_fast_path_on(struct tcp_sock *tp)
621 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
624 static inline void tcp_fast_path_check(struct sock *sk)
626 struct tcp_sock *tp = tcp_sk(sk);
628 if (skb_queue_empty(&tp->out_of_order_queue) &&
630 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
632 tcp_fast_path_on(tp);
635 /* Compute the actual rto_min value */
636 static inline u32 tcp_rto_min(struct sock *sk)
638 const struct dst_entry *dst = __sk_dst_get(sk);
639 u32 rto_min = TCP_RTO_MIN;
641 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
642 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
646 /* Compute the actual receive window we are currently advertising.
647 * Rcv_nxt can be after the window if our peer push more data
648 * than the offered window.
650 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
652 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
659 /* Choose a new window, without checks for shrinking, and without
660 * scaling applied to the result. The caller does these things
661 * if necessary. This is a "raw" window selection.
663 extern u32 __tcp_select_window(struct sock *sk);
665 void tcp_send_window_probe(struct sock *sk);
667 /* TCP timestamps are only 32-bits, this causes a slight
668 * complication on 64-bit systems since we store a snapshot
669 * of jiffies in the buffer control blocks below. We decided
670 * to use only the low 32-bits of jiffies and hide the ugly
671 * casts with the following macro.
673 #define tcp_time_stamp ((__u32)(jiffies))
675 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
677 #define TCPHDR_FIN 0x01
678 #define TCPHDR_SYN 0x02
679 #define TCPHDR_RST 0x04
680 #define TCPHDR_PSH 0x08
681 #define TCPHDR_ACK 0x10
682 #define TCPHDR_URG 0x20
683 #define TCPHDR_ECE 0x40
684 #define TCPHDR_CWR 0x80
686 /* This is what the send packet queuing engine uses to pass
687 * TCP per-packet control information to the transmission code.
688 * We also store the host-order sequence numbers in here too.
689 * This is 44 bytes if IPV6 is enabled.
690 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
694 struct inet_skb_parm h4;
695 #if IS_ENABLED(CONFIG_IPV6)
696 struct inet6_skb_parm h6;
698 } header; /* For incoming frames */
699 __u32 seq; /* Starting sequence number */
700 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
701 __u32 when; /* used to compute rtt's */
702 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
704 __u8 sacked; /* State flags for SACK/FACK. */
705 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
706 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
707 #define TCPCB_LOST 0x04 /* SKB is lost */
708 #define TCPCB_TAGBITS 0x07 /* All tag bits */
709 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
710 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
712 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
714 __u32 ack_seq; /* Sequence number ACK'd */
717 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
719 /* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
721 * If we receive a SYN packet with these bits set, it means a network is
722 * playing bad games with TOS bits. In order to avoid possible false congestion
723 * notifications, we disable TCP ECN negociation.
726 TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb,
729 const struct tcphdr *th = tcp_hdr(skb);
731 if (net->ipv4.sysctl_tcp_ecn && th->ece && th->cwr &&
732 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
733 inet_rsk(req)->ecn_ok = 1;
736 /* Due to TSO, an SKB can be composed of multiple actual
737 * packets. To keep these tracked properly, we use this.
739 static inline int tcp_skb_pcount(const struct sk_buff *skb)
741 return skb_shinfo(skb)->gso_segs;
744 /* This is valid iff tcp_skb_pcount() > 1. */
745 static inline int tcp_skb_mss(const struct sk_buff *skb)
747 return skb_shinfo(skb)->gso_size;
750 /* Events passed to congestion control interface */
752 CA_EVENT_TX_START, /* first transmit when no packets in flight */
753 CA_EVENT_CWND_RESTART, /* congestion window restart */
754 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
755 CA_EVENT_LOSS, /* loss timeout */
756 CA_EVENT_FAST_ACK, /* in sequence ack */
757 CA_EVENT_SLOW_ACK, /* other ack */
761 * Interface for adding new TCP congestion control handlers
763 #define TCP_CA_NAME_MAX 16
764 #define TCP_CA_MAX 128
765 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
767 #define TCP_CONG_NON_RESTRICTED 0x1
768 #define TCP_CONG_RTT_STAMP 0x2
770 struct tcp_congestion_ops {
771 struct list_head list;
774 /* initialize private data (optional) */
775 void (*init)(struct sock *sk);
776 /* cleanup private data (optional) */
777 void (*release)(struct sock *sk);
779 /* return slow start threshold (required) */
780 u32 (*ssthresh)(struct sock *sk);
781 /* lower bound for congestion window (optional) */
782 u32 (*min_cwnd)(const struct sock *sk);
783 /* do new cwnd calculation (required) */
784 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
785 /* call before changing ca_state (optional) */
786 void (*set_state)(struct sock *sk, u8 new_state);
787 /* call when cwnd event occurs (optional) */
788 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
789 /* new value of cwnd after loss (optional) */
790 u32 (*undo_cwnd)(struct sock *sk);
791 /* hook for packet ack accounting (optional) */
792 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
793 /* get info for inet_diag (optional) */
794 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
796 char name[TCP_CA_NAME_MAX];
797 struct module *owner;
800 extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
801 extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
803 extern void tcp_init_congestion_control(struct sock *sk);
804 extern void tcp_cleanup_congestion_control(struct sock *sk);
805 extern int tcp_set_default_congestion_control(const char *name);
806 extern void tcp_get_default_congestion_control(char *name);
807 extern void tcp_get_available_congestion_control(char *buf, size_t len);
808 extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
809 extern int tcp_set_allowed_congestion_control(char *allowed);
810 extern int tcp_set_congestion_control(struct sock *sk, const char *name);
811 extern void tcp_slow_start(struct tcp_sock *tp);
812 extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
814 extern struct tcp_congestion_ops tcp_init_congestion_ops;
815 extern u32 tcp_reno_ssthresh(struct sock *sk);
816 extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
817 extern u32 tcp_reno_min_cwnd(const struct sock *sk);
818 extern struct tcp_congestion_ops tcp_reno;
820 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
822 struct inet_connection_sock *icsk = inet_csk(sk);
824 if (icsk->icsk_ca_ops->set_state)
825 icsk->icsk_ca_ops->set_state(sk, ca_state);
826 icsk->icsk_ca_state = ca_state;
829 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
831 const struct inet_connection_sock *icsk = inet_csk(sk);
833 if (icsk->icsk_ca_ops->cwnd_event)
834 icsk->icsk_ca_ops->cwnd_event(sk, event);
837 /* These functions determine how the current flow behaves in respect of SACK
838 * handling. SACK is negotiated with the peer, and therefore it can vary
839 * between different flows.
841 * tcp_is_sack - SACK enabled
842 * tcp_is_reno - No SACK
843 * tcp_is_fack - FACK enabled, implies SACK enabled
845 static inline int tcp_is_sack(const struct tcp_sock *tp)
847 return tp->rx_opt.sack_ok;
850 static inline bool tcp_is_reno(const struct tcp_sock *tp)
852 return !tcp_is_sack(tp);
855 static inline bool tcp_is_fack(const struct tcp_sock *tp)
857 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
860 static inline void tcp_enable_fack(struct tcp_sock *tp)
862 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
865 /* TCP early-retransmit (ER) is similar to but more conservative than
866 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
868 static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
870 tp->do_early_retrans = sysctl_tcp_early_retrans &&
871 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack &&
872 sysctl_tcp_reordering == 3;
875 static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
877 tp->do_early_retrans = 0;
880 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
882 return tp->sacked_out + tp->lost_out;
885 /* This determines how many packets are "in the network" to the best
886 * of our knowledge. In many cases it is conservative, but where
887 * detailed information is available from the receiver (via SACK
888 * blocks etc.) we can make more aggressive calculations.
890 * Use this for decisions involving congestion control, use just
891 * tp->packets_out to determine if the send queue is empty or not.
893 * Read this equation as:
895 * "Packets sent once on transmission queue" MINUS
896 * "Packets left network, but not honestly ACKed yet" PLUS
897 * "Packets fast retransmitted"
899 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
901 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
904 #define TCP_INFINITE_SSTHRESH 0x7fffffff
906 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
908 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
911 static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
913 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
914 (1 << inet_csk(sk)->icsk_ca_state);
917 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
918 * The exception is cwnd reduction phase, when cwnd is decreasing towards
921 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
923 const struct tcp_sock *tp = tcp_sk(sk);
925 if (tcp_in_cwnd_reduction(sk))
926 return tp->snd_ssthresh;
928 return max(tp->snd_ssthresh,
929 ((tp->snd_cwnd >> 1) +
930 (tp->snd_cwnd >> 2)));
933 /* Use define here intentionally to get WARN_ON location shown at the caller */
934 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
936 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
937 extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
939 /* The maximum number of MSS of available cwnd for which TSO defers
940 * sending if not using sysctl_tcp_tso_win_divisor.
942 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
947 /* Slow start with delack produces 3 packets of burst, so that
948 * it is safe "de facto". This will be the default - same as
949 * the default reordering threshold - but if reordering increases,
950 * we must be able to allow cwnd to burst at least this much in order
951 * to not pull it back when holes are filled.
953 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
955 return tp->reordering;
958 /* Returns end sequence number of the receiver's advertised window */
959 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
961 return tp->snd_una + tp->snd_wnd;
963 extern bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
965 static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
966 const struct sk_buff *skb)
969 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
972 static inline void tcp_check_probe_timer(struct sock *sk)
974 const struct tcp_sock *tp = tcp_sk(sk);
975 const struct inet_connection_sock *icsk = inet_csk(sk);
977 if (!tp->packets_out && !icsk->icsk_pending)
978 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
979 icsk->icsk_rto, TCP_RTO_MAX);
982 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
987 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
993 * Calculate(/check) TCP checksum
995 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
996 __be32 daddr, __wsum base)
998 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1001 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1003 return __skb_checksum_complete(skb);
1006 static inline bool tcp_checksum_complete(struct sk_buff *skb)
1008 return !skb_csum_unnecessary(skb) &&
1009 __tcp_checksum_complete(skb);
1012 /* Prequeue for VJ style copy to user, combined with checksumming. */
1014 static inline void tcp_prequeue_init(struct tcp_sock *tp)
1016 tp->ucopy.task = NULL;
1018 tp->ucopy.memory = 0;
1019 skb_queue_head_init(&tp->ucopy.prequeue);
1020 #ifdef CONFIG_NET_DMA
1021 tp->ucopy.dma_chan = NULL;
1022 tp->ucopy.wakeup = 0;
1023 tp->ucopy.pinned_list = NULL;
1024 tp->ucopy.dma_cookie = 0;
1028 extern bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
1033 static const char *statename[]={
1034 "Unused","Established","Syn Sent","Syn Recv",
1035 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1036 "Close Wait","Last ACK","Listen","Closing"
1039 extern void tcp_set_state(struct sock *sk, int state);
1041 extern void tcp_done(struct sock *sk);
1043 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1046 rx_opt->num_sacks = 0;
1049 /* Determine a window scaling and initial window to offer. */
1050 extern void tcp_select_initial_window(int __space, __u32 mss,
1051 __u32 *rcv_wnd, __u32 *window_clamp,
1052 int wscale_ok, __u8 *rcv_wscale,
1053 __u32 init_rcv_wnd);
1055 static inline int tcp_win_from_space(int space)
1057 return sysctl_tcp_adv_win_scale<=0 ?
1058 (space>>(-sysctl_tcp_adv_win_scale)) :
1059 space - (space>>sysctl_tcp_adv_win_scale);
1062 /* Note: caller must be prepared to deal with negative returns */
1063 static inline int tcp_space(const struct sock *sk)
1065 return tcp_win_from_space(sk->sk_rcvbuf -
1066 atomic_read(&sk->sk_rmem_alloc));
1069 static inline int tcp_full_space(const struct sock *sk)
1071 return tcp_win_from_space(sk->sk_rcvbuf);
1074 static inline void tcp_openreq_init(struct request_sock *req,
1075 struct tcp_options_received *rx_opt,
1076 struct sk_buff *skb)
1078 struct inet_request_sock *ireq = inet_rsk(req);
1080 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1082 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1083 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
1084 tcp_rsk(req)->snt_synack = 0;
1085 req->mss = rx_opt->mss_clamp;
1086 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1087 ireq->tstamp_ok = rx_opt->tstamp_ok;
1088 ireq->sack_ok = rx_opt->sack_ok;
1089 ireq->snd_wscale = rx_opt->snd_wscale;
1090 ireq->wscale_ok = rx_opt->wscale_ok;
1093 ireq->rmt_port = tcp_hdr(skb)->source;
1094 ireq->loc_port = tcp_hdr(skb)->dest;
1097 /* Compute time elapsed between SYNACK and the ACK completing 3WHS */
1098 static inline void tcp_synack_rtt_meas(struct sock *sk,
1099 struct request_sock *req)
1101 if (tcp_rsk(req)->snt_synack)
1102 tcp_valid_rtt_meas(sk,
1103 tcp_time_stamp - tcp_rsk(req)->snt_synack);
1106 extern void tcp_enter_memory_pressure(struct sock *sk);
1108 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1110 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1113 static inline int keepalive_time_when(const struct tcp_sock *tp)
1115 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1118 static inline int keepalive_probes(const struct tcp_sock *tp)
1120 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1123 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1125 const struct inet_connection_sock *icsk = &tp->inet_conn;
1127 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1128 tcp_time_stamp - tp->rcv_tstamp);
1131 static inline int tcp_fin_time(const struct sock *sk)
1133 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1134 const int rto = inet_csk(sk)->icsk_rto;
1136 if (fin_timeout < (rto << 2) - (rto >> 1))
1137 fin_timeout = (rto << 2) - (rto >> 1);
1142 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1145 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1147 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1150 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1151 * then following tcp messages have valid values. Ignore 0 value,
1152 * or else 'negative' tsval might forbid us to accept their packets.
1154 if (!rx_opt->ts_recent)
1159 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1162 if (tcp_paws_check(rx_opt, 0))
1165 /* RST segments are not recommended to carry timestamp,
1166 and, if they do, it is recommended to ignore PAWS because
1167 "their cleanup function should take precedence over timestamps."
1168 Certainly, it is mistake. It is necessary to understand the reasons
1169 of this constraint to relax it: if peer reboots, clock may go
1170 out-of-sync and half-open connections will not be reset.
1171 Actually, the problem would be not existing if all
1172 the implementations followed draft about maintaining clock
1173 via reboots. Linux-2.2 DOES NOT!
1175 However, we can relax time bounds for RST segments to MSL.
1177 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1182 static inline void tcp_mib_init(struct net *net)
1185 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1186 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1187 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1188 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1192 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1194 tp->lost_skb_hint = NULL;
1195 tp->scoreboard_skb_hint = NULL;
1198 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1200 tcp_clear_retrans_hints_partial(tp);
1201 tp->retransmit_skb_hint = NULL;
1207 union tcp_md5_addr {
1209 #if IS_ENABLED(CONFIG_IPV6)
1214 /* - key database */
1215 struct tcp_md5sig_key {
1216 struct hlist_node node;
1218 u8 family; /* AF_INET or AF_INET6 */
1219 union tcp_md5_addr addr;
1220 u8 key[TCP_MD5SIG_MAXKEYLEN];
1221 struct rcu_head rcu;
1225 struct tcp_md5sig_info {
1226 struct hlist_head head;
1227 struct rcu_head rcu;
1230 /* - pseudo header */
1231 struct tcp4_pseudohdr {
1239 struct tcp6_pseudohdr {
1240 struct in6_addr saddr;
1241 struct in6_addr daddr;
1243 __be32 protocol; /* including padding */
1246 union tcp_md5sum_block {
1247 struct tcp4_pseudohdr ip4;
1248 #if IS_ENABLED(CONFIG_IPV6)
1249 struct tcp6_pseudohdr ip6;
1253 /* - pool: digest algorithm, hash description and scratch buffer */
1254 struct tcp_md5sig_pool {
1255 struct hash_desc md5_desc;
1256 union tcp_md5sum_block md5_blk;
1260 extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1261 const struct sock *sk,
1262 const struct request_sock *req,
1263 const struct sk_buff *skb);
1264 extern int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1265 int family, const u8 *newkey,
1266 u8 newkeylen, gfp_t gfp);
1267 extern int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1269 extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1270 struct sock *addr_sk);
1272 #ifdef CONFIG_TCP_MD5SIG
1273 extern struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1274 const union tcp_md5_addr *addr, int family);
1275 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1277 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1278 const union tcp_md5_addr *addr,
1283 #define tcp_twsk_md5_key(twsk) NULL
1286 extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *);
1287 extern void tcp_free_md5sig_pool(void);
1289 extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1290 extern void tcp_put_md5sig_pool(void);
1292 extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1293 extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1294 unsigned int header_len);
1295 extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1296 const struct tcp_md5sig_key *key);
1298 /* From tcp_fastopen.c */
1299 extern void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1300 struct tcp_fastopen_cookie *cookie,
1301 int *syn_loss, unsigned long *last_syn_loss);
1302 extern void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1303 struct tcp_fastopen_cookie *cookie,
1305 struct tcp_fastopen_request {
1306 /* Fast Open cookie. Size 0 means a cookie request */
1307 struct tcp_fastopen_cookie cookie;
1308 struct msghdr *data; /* data in MSG_FASTOPEN */
1309 u16 copied; /* queued in tcp_connect() */
1311 void tcp_free_fastopen_req(struct tcp_sock *tp);
1313 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1314 int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1315 void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc);
1317 #define TCP_FASTOPEN_KEY_LENGTH 16
1319 /* Fastopen key context */
1320 struct tcp_fastopen_context {
1321 struct crypto_cipher __rcu *tfm;
1322 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1323 struct rcu_head rcu;
1326 /* write queue abstraction */
1327 static inline void tcp_write_queue_purge(struct sock *sk)
1329 struct sk_buff *skb;
1331 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1332 sk_wmem_free_skb(sk, skb);
1334 tcp_clear_all_retrans_hints(tcp_sk(sk));
1337 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1339 return skb_peek(&sk->sk_write_queue);
1342 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1344 return skb_peek_tail(&sk->sk_write_queue);
1347 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1348 const struct sk_buff *skb)
1350 return skb_queue_next(&sk->sk_write_queue, skb);
1353 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1354 const struct sk_buff *skb)
1356 return skb_queue_prev(&sk->sk_write_queue, skb);
1359 #define tcp_for_write_queue(skb, sk) \
1360 skb_queue_walk(&(sk)->sk_write_queue, skb)
1362 #define tcp_for_write_queue_from(skb, sk) \
1363 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1365 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1366 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1368 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1370 return sk->sk_send_head;
1373 static inline bool tcp_skb_is_last(const struct sock *sk,
1374 const struct sk_buff *skb)
1376 return skb_queue_is_last(&sk->sk_write_queue, skb);
1379 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1381 if (tcp_skb_is_last(sk, skb))
1382 sk->sk_send_head = NULL;
1384 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1387 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1389 if (sk->sk_send_head == skb_unlinked)
1390 sk->sk_send_head = NULL;
1393 static inline void tcp_init_send_head(struct sock *sk)
1395 sk->sk_send_head = NULL;
1398 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1400 __skb_queue_tail(&sk->sk_write_queue, skb);
1403 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1405 __tcp_add_write_queue_tail(sk, skb);
1407 /* Queue it, remembering where we must start sending. */
1408 if (sk->sk_send_head == NULL) {
1409 sk->sk_send_head = skb;
1411 if (tcp_sk(sk)->highest_sack == NULL)
1412 tcp_sk(sk)->highest_sack = skb;
1416 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1418 __skb_queue_head(&sk->sk_write_queue, skb);
1421 /* Insert buff after skb on the write queue of sk. */
1422 static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1423 struct sk_buff *buff,
1426 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1429 /* Insert new before skb on the write queue of sk. */
1430 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1431 struct sk_buff *skb,
1434 __skb_queue_before(&sk->sk_write_queue, skb, new);
1436 if (sk->sk_send_head == skb)
1437 sk->sk_send_head = new;
1440 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1442 __skb_unlink(skb, &sk->sk_write_queue);
1445 static inline bool tcp_write_queue_empty(struct sock *sk)
1447 return skb_queue_empty(&sk->sk_write_queue);
1450 static inline void tcp_push_pending_frames(struct sock *sk)
1452 if (tcp_send_head(sk)) {
1453 struct tcp_sock *tp = tcp_sk(sk);
1455 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1459 /* Start sequence of the skb just after the highest skb with SACKed
1460 * bit, valid only if sacked_out > 0 or when the caller has ensured
1461 * validity by itself.
1463 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1465 if (!tp->sacked_out)
1468 if (tp->highest_sack == NULL)
1471 return TCP_SKB_CB(tp->highest_sack)->seq;
1474 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1476 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1477 tcp_write_queue_next(sk, skb);
1480 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1482 return tcp_sk(sk)->highest_sack;
1485 static inline void tcp_highest_sack_reset(struct sock *sk)
1487 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1490 /* Called when old skb is about to be deleted (to be combined with new skb) */
1491 static inline void tcp_highest_sack_combine(struct sock *sk,
1492 struct sk_buff *old,
1493 struct sk_buff *new)
1495 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1496 tcp_sk(sk)->highest_sack = new;
1499 /* Determines whether this is a thin stream (which may suffer from
1500 * increased latency). Used to trigger latency-reducing mechanisms.
1502 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1504 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1508 enum tcp_seq_states {
1509 TCP_SEQ_STATE_LISTENING,
1510 TCP_SEQ_STATE_OPENREQ,
1511 TCP_SEQ_STATE_ESTABLISHED,
1512 TCP_SEQ_STATE_TIME_WAIT,
1515 int tcp_seq_open(struct inode *inode, struct file *file);
1517 struct tcp_seq_afinfo {
1520 const struct file_operations *seq_fops;
1521 struct seq_operations seq_ops;
1524 struct tcp_iter_state {
1525 struct seq_net_private p;
1527 enum tcp_seq_states state;
1528 struct sock *syn_wait_sk;
1529 int bucket, offset, sbucket, num;
1534 extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1535 extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1537 extern struct request_sock_ops tcp_request_sock_ops;
1538 extern struct request_sock_ops tcp6_request_sock_ops;
1540 extern void tcp_v4_destroy_sock(struct sock *sk);
1542 extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1543 extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
1544 netdev_features_t features);
1545 extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1546 struct sk_buff *skb);
1547 extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1548 struct sk_buff *skb);
1549 extern int tcp_gro_complete(struct sk_buff *skb);
1550 extern int tcp4_gro_complete(struct sk_buff *skb);
1552 #ifdef CONFIG_PROC_FS
1553 extern int tcp4_proc_init(void);
1554 extern void tcp4_proc_exit(void);
1557 /* TCP af-specific functions */
1558 struct tcp_sock_af_ops {
1559 #ifdef CONFIG_TCP_MD5SIG
1560 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1561 struct sock *addr_sk);
1562 int (*calc_md5_hash) (char *location,
1563 struct tcp_md5sig_key *md5,
1564 const struct sock *sk,
1565 const struct request_sock *req,
1566 const struct sk_buff *skb);
1567 int (*md5_parse) (struct sock *sk,
1568 char __user *optval,
1573 struct tcp_request_sock_ops {
1574 #ifdef CONFIG_TCP_MD5SIG
1575 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1576 struct request_sock *req);
1577 int (*calc_md5_hash) (char *location,
1578 struct tcp_md5sig_key *md5,
1579 const struct sock *sk,
1580 const struct request_sock *req,
1581 const struct sk_buff *skb);
1585 extern void tcp_v4_init(void);
1586 extern void tcp_init(void);